Project Summary Self-testing of HIV viral load would significantly reduce new infections and provide methods for HIV positive individuals to monitor viral load in the privacy of their own homes. Testing at home followed by analysis of the aggregate data would also assist health care providers, program managers and policy makers to determine the impact of new clinical trials and other interventions. The challenges involved in developing self-testing HIV viral load tests are formidable; for example, the current laboratory tests use milliliters of venous blood extracted in a clinical setting. For self-testing, only microliters of finger stick blood are used, which has low HIV viral copy numbers. To meet these challenges, an interdisciplinary team of scientists with a proven track record has been assembled; the team includes expertise from Chemistry, Biomedical Engineering and Virology. The team has successfully demonstrated the ability to detect influenza virus and measure antiviral susceptibility using repurposed glucose meters in less than 15 minutes. Here, the strategy focuses on detecting HIV protease activity using repurposed glucometers and correlating protease activity to viral load. Since low copy numbers are present in a sample, signal amplification is necessary. In specific aim 1 (R61 phase), a caspase-3 proenzyme bearing HIV protease peptide substrate will be produced. Exposure to HIV protease will result in an active caspase-3 enzyme, which will convert an electrochemically inactive substrate to produce an electrochemically active analyte for detection and qualification with glucometers. In specific aim 2 (R61 phase), mesoporous silica beads capped with anti-HIV protease antibody or peptide substrate will be produced. Inorganic catalysts will be embedded inside the pores of the beads. Exposure to HIV protease will uncap the antibodies or peptide substrate and release the catalysts, which will reach with a substrate to produce an electrochemically active analyte for detection with glucometers. The first two specific aims are designed to be independent of each other to de-risk this high risk, high impact project. Successful execution of specific aims 1 and 2 will lead to specific aim 3 (R33 phase), which would involve testing of the virus from culture and from HIV positive patients. The results from the R33 phase will be compared and contrasted to laboratory based methods including highly accurate PCR methods. At the end of the project period, proof of principle for a novel method that uses repurposed glucose meters to detect HIV during the acute phase and when the viral load increases due to antiviral resistance or discontinuing treatment will be established.